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Adaptation of Plantago plants to environmental conditions: the role of carbohydrate balance
Skulníková, Barbora ; Konrádová, Hana (advisor) ; Lhotáková, Zuzana (referee)
Sorbitol is a linear sugar alcohol which is, together with sucrose, the primary photosynthetic product in the Plantaginaceae family. Sorbitol and sucrose are used for long-distance transport of photosynthetically fixed carbon via phloem. Many plant species accumulate sugar alcohols during drought or salt stresses, and it leads to higher tolerance to these stress conditions. The aim of this diploma thesis is to describe selected metabolic and structure differences with a focus on the sorbitol and sucrose balance, in two Plantago species - glycophytic Plantago lanceolata and halophytic Plantago maritima, which differ in life strategies. The plants were cultivated hydroponically in Araponics boxes. Previous results of our team show, that sorbitol accumulates in Plantago leaves up to ten-times higher concentrations compared with sucrose. This difference is deepened when the plants are exposed to salt stress. Sorbitol to sucrose ratios vary between vascular tissue and phloem sap. We assume that increased salt tolerance of P. maritima is based on the different distribution of assimilates through the plant, and by their partitioning between metabolic, storage and transport pools in mature leaf, which also manifests under non-stress conditions. In both genotypes, I compared growth rates under standard...
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Flexibility of cyclitol metabolism as a component of effective plant defense against water scarcity
Skulníková, Barbora ; Konrádová, Hana (advisor) ; Lhotáková, Zuzana (referee)
This bachelor thesis is focused on plant defence mechanisms against drought stress and salinity stress associated with the production of compatible solutes, while attention is paid to the accumulation of cyclic sugar alcohols, myo-inositol and its methylated derivatives. It describes the occurrence of these substances, their biosynthesis and function in plants. Another part of this thesis focuses on the crystalline ice plant (Mesembranthemum crystallinum), which is an important producer of these substances and serves as a model used to study the stress response in plants. It describes its life cycle and especially the mechanisms that makes it resistant to drought stress and salinity. The last chapter is dedicated to the knowledge gained through the study of transgenic plants, which were prepared using genes from crystalline ice plant and other stress tolerant plants.
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